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ENUM Tutorial. ENUM Forum June 3, 2003 Steven D. Lind, AT&T GEN0075R0. Disclaimer. Heavily borrowed from: Patrik Faltstr öm’s IETF presentation to February 2002 ITU Workshop on ENUM AT&T/ENUM Forum presentation to December 2002 SG2 meeting Added some telecomm perspective. Assumption. - PowerPoint PPT Presentation
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ENUM Tutorial
ENUM Forum
June 3, 2003
Steven D. Lind, AT&T
GEN0075R0
Disclaimer
• Heavily borrowed from:– Patrik Faltström’s IETF presentation to
February 2002 ITU Workshop on ENUM – AT&T/ENUM Forum presentation to
December 2002 SG2 meeting
• Added some telecomm perspective
Assumption
• Use of standard telephone numbers is not going away– PSTN/analog terminals
are going to be around– IP phones use 12-
button keypad– Globally unique
identifier that has established familiarity with end users
Problem statements
• How do network elements (gateways, SIP servers etc) find services on the Internet if you only have a telephone (E.164) number?
• How can subscribers define their preferences for incoming communications?
More Problem Statements
• How do you address an IP-based voice terminal from the PSTN?
• For a call that starts out as VoIP, how do you know to keep the call on the IP-plane (as opposed to the PSTN) for a dialed telephone number if the customer is not yours?
With ENUM, Only One
tel:+46-8-971234
mailto:[email protected]
tel:+46-706051234
tel:+46-706051234
Give this number to friends:+46-8-971234
ENUM
Solution in short
• Put domain names derived from telephone numbers in the global domain name system, DNS
• IETF ENUM Working Group created to solve the problem of using the DNS for:
–domain name in– [Numbers re-formatted as domain names] –URI out– [mailto, sip, tel, http or other URI scheme]
• Solution: NAPTR records• Use the URI’s for the communication
ENUM in a nutshell
• take phone number +46-8-6859131
• turn into domain name 1.3.1.9.5.8.6.8.6.4.e164.arpa.
• return list of URI’ssip:[email protected]
• ask the DNS
mailto:[email protected]
Step 1
• Take an E.164 number and create a fully qualified domain name in a single highly defined and structured domain
• +46-8-971234• +468971234• 4.3.2.1.7.9.8.6.4.e164.arpa.
The input to theNAPTR algorithm
Step 1 - Explanation
• Each digit can become a definable and distributed “zone” in DNS terms
• Delegation can (doesn’t have to) happen at every digit, including at last digit
• Zones such as country codes, area codes or primary delegated blocks of numbers can be delegated as well as individual numbers
• DNS defines authoritative name servers for NAPTR/service resource records
Step 2
• Lookup NAPTR RR’s in DNS, and apply NAPTR/ENUM algorithm4.3.2.1.7.9.8.6.4.e164.arpa.!^.*$!mailto:[email protected]!!^+46(.*)$!ldap://ldap.telco.se/cn=0\1!
• Use rewrite rules using regular expressions which operate on the E.164 number (+468971234)
Regular Expressions
• For ENUM, the NAPTR regexp field may yield an (unchanged) URL
• !<regexp>!<string>!– “Match <regexp> on original E.164,
and apply rewrite rule <string>” ^ - Match beginning $ - Match end . - Match any character.* - Match any number of any character() - Grouping, \n in <string> is replaced with group number ‘n’ in <regexp>
Step 2 in detail
• $ORIGIN 4.3.2.1.7.9.8.6.4.e164.arpa.• IN NAPTR 10 10 ”U” ”mailto+E2U”
”!^.*$!mailto:[email protected]!”• IN NAPTR 20 10 ”U” ”ldap+E2U”
”!^+46(.*)$!ldap://ldap.telco.se/cn=0\1”
• Note that no line break should be in the records
Tier 0
Tier 1
Tier 2
DomainName
System
ApplicationServiceProvider
Registrar
Registry
ENUMEnabled
Applications
Provisioning
• voice• fax• messaging & presence• email• web pages
Authentication &
ValidationEntities
The Public ENUM Infrastructure
$ORIGIN e164.arpa. 3.7.9.1 IN NS nsnanp.enum.com . 4.4 IN NS sweden_enum.com .…
$ORIGIN 3.7.9.1.e164.arpa. 7.9.7.6.6.3.2 IN NS e164.att.net .8.9.7.6.6.3.2 IN NS e164.xyz.com .…
$ORIGIN 7.9.7.6.6.3.2.3.7.9.1.e164.arpa. IN NAPTR 100 10 "u" "sip+E2U" "!^.*$!sip:[email protected]!" .
e164.arpa
Tier 0 (Country Code Registry)
nsnanp.enum.com(3.7.9.1.e164.arpa)
Tier 1 (Telephone Number Registry)
e164.att.net
Tier 2 (Application Information)
International Implementation worked in IETF and ITU-T
National Implementation worked in ENUM Forum (US)
sweden_enum.com(4.4.e164.arpa)
…
Delegation of Country Codein Tier 0
• Draft Recommendation E.A-ENUM in progress• Interim Procedures in place between IAB/ISOC
and ITU-TSB– Use of e164.arpa pending outcome of Recommendation– Requests must be authenticated by TSB before RIPE-
NCC can act– Country Code must be valid and assigned– Position of National Numbering Administrator must be
known and must opt-in
• Similar situation for shared Network codes and codes for Groups of Countries (e.g., ETNS)
Country Code Delegationsas of 23 May 2003
E.164 Country Code
Country
Delegee Date of TSB Approval dd/mm/yy
246 Diego Garcia Government 12/08/02 247 Ascension Government 12/08/02
290 Saint Helena Government 12/08/02 31 Netherlands Ministry 23/05/02 33 France DiGITIP (Government) 28/03/03 358 Finland Finnish Communications
Regulatory Authority 26/02/03
36 Hungary CHIP/ISzT 15/07/02 40 Romania MinCom 10/12/02
43 Austria Regulator 11/06/02 44 UK DTI/Nominum 16/05/02 46 Sweden NPTA 10/12/02 48 Poland NASK 18/07/02 49 Germany DENIC 16/05/02 55 Brazil Brazilian Internet Registry 19/07/02 86 China (c) CNNIC 02/09/02
878 10 (a) VISIONng 16/05/02 971 United Arab
Emirates Etisalat 13/01/03
991 001 (b) NeuStar 02/02/01
Notes: (a) This is a Universal Personal Telephony (UPT) code. (b) This is a trial code granted to NeuStar for a limited period. The period expires on 2 November
2003. (c) This is a temporary authorization for ENUM global TLD trial and evaluation. This delegation
will end on 30 June 2003. If the ITU Interim Procedure is discontinued before then, or if the Recommendation E.A-ENUM is approved before 30 June 2003, the delegation will be turned into an objection.
National Implementation in the US• ENUM Forum organized in August 2001 to
address technical specifications• “ENUM Forum Specifications for US
Implementation of ENUM” (6000_1_0) approved and reviewed with USG in February, 2003– Requirements for Tier 1 Registry
– Specifications and guidelines for Registrar & Tier 2 nameserver
• Need mechanism for contracting with Tier 1 operators
Requirements Document
• Reference Architecture• Tier 1 Registry Operations, Security, & Admin• Tier 1 Performance Specifications• Privacy Considerations• Provisioning• Registrar Requirements• Authentication & Authorization• Tier 2 Requirements & Guidelines• Conflict Resolution• Issues Out of Scope
Reference Architecture
Tier 1Registry
Tier 0
Root
Tier 2Provider
RegistrantRegistrant RegistrarRegistrar
Reference Architecture
• Registrar• Registrant• Tier 1 Registry
o Does not address non geographic numbers• Tier 2 Service Provider
o Tier 2 contains the NAPTR records or delegations • Interfaces• Issue:
o One or More Tier 1 Providers– Delegation at Tier 0 by NPA
Tier 1 Aspects
• Tier 1 Operationso Zone Information (aka zone files)o ContactInfo (aka WhoIs)o Reporting, backup, escrow & performance
requirements• Performance Aspects
o DNS Performanceo EPP Interfaces
• Tier 1 Security• Administrative Aspects
o Dispute Resolutiono Data Collection and Privacy
Privacy Considerations
• Registrant Choice• Privacy Analysis• Open Disclosure of Registrant Information in DNS• Information Handling During Registration and
Provisioning• Contact Info• Fair Information Practices
Provisioning
Tier 2Nameserver
RegistrarRegistrarTier 1
RegistryRegistrantRegistrant
Application ServiceProvider
Application ServiceProvider
Authentication & Validation Entities
Provisioning Aspects
• Registrar Requirementso Registrant Validation & Authenticationo Dispute Resolutiono Registrar Infrastructure Requirementso Recommended Practices & Requirementso Various Scenarios
- Information Flows
• Tier 2o Mostly Guidelines – SomeSome Requirementso Tier 2 may be self-provided or from a commercial 3rd partyo Interfaces & Interactionso Performance Recommendations
ExamplesDNS-Server
InternetPSTN
Cal
led
par
ty
Cal
ling
par
ty
SIP-Server
SIP-Server
Gateway
Gateway
“Call setup”
PSTN to VoIP Call via SIP
Sipsip:[email protected]
Query1.3.1.9.5.8.6.8.6.4.e164.arpa.?
Dial+4686859131
DNS-Server
Sip serverGateway
Responsesip:[email protected]
VoIP via SIP to VoIPDNS-Server
“ENUM”
SIP-Server
SIP-Server
Gateway
Gateway
VoIP via PSTN to PSTN
DNS-Server
“ENUM”
SIP-Server
SIP-Server
Gateway
Gateway
Future Actions
• Address implementation issues– Contracting model
– Integration/separation of North American countries
– Number of Tier 1 operators
• Address Non-geographic numbers (specifically 8YY Toll Free)– Can’t be cleanly separated by North American country
– Has unique provisioning requirements
